Speed-changing cam device for zigzag sewing machines



1962 HIDEO IIDA EI'AL 3,064,603

SPEED-CHANGING CAM DEVICE FOR Z IGZAG SEWING MACHINES Filed 001.. 21,1959 4 Sheets-Sheet l Nov. 20, 1962 HIDEO HDA EI'AL SPEED-CHANGING CAMDEVICE FOR ZIGZAG SEWING MACHINES 4 Sheets-Sheet 2 Filed Oct. 21, 1959NOV. 20, 1962 HIDEQ "DA r 3,064,603

SPEED-CHANGING CAM DEVICE FOR ZIGZAG SEWING MACHINES Filed Oct. 21,3.959 4 Sheets-Sheet 3 1962 HIDEO llDA EFAL 3,06

SPEED-CHANGING CAM DEVICE FOR ZIGZAG SEWING MACHINES Filed 001;. 21,1959 4 Sheets-Sheet -4 rates This invention relates to a speed-changingcam device for zigzag sewing machines which automatically regulates, bymeans of a cam mechanism moving synchronously with the main shaft, themechanism which regulates the fabric feeding motion or the sideoscillation motion of the needle of a sewing machine.

It is an object of this invention to provide a device wherein, by anextremely simple operation, the rotational speed ratio between theautomatic operation cam shaft and the main shaft can be changedsteplessly and, moreover, quietly and positively.

In the conventional automatic zigzag sewing machines of the cam-changingtype, it has been necessary to provide a large number of different camsas accessories, because only one kind of pattern could be obtained withone cam, this necessity being ineflicient and uneconomical in time andcost. In the present invention, however, by a simple manipulation of apattern regulating lever installed on, and co-axially with, a zigzagamplitude control knob, sewing of numerous patterns of different spatialpitch can be carried out with the use of one cam, and various excellentresults can be thus obtained, thereby enabling the attainment of theaforementioned object and other objects as will be apparent from thefollowing disclosure.

The details of theinvention will be more clearly apparent by referenceto the following detailed description of one representative embodimentof the invention when taken in connection with the accompanyingdrawings, in which:

FIG. 1 is a perspective view of the principal mechanism of an ordinaryzigzag sewing machine, of general type, to which the device of thepresent invention is to be installed;

FIG. 2 is a plan View, partially in section and with parts cut away, ofthe mechanism of FIG. 1 to which the device of the present invention hasbeen installed;

FIG. 3 and 4 are elevational views, in section with parts cut away,taken along planes IIIIII and IV-IV, respectively, of FIG. 2;

FIG. 5 is similarly an elevational view, in section, taken along theplane VV of FIG. 2;

FIGS. 6, 7, and 8 are plan views for explanation of the manual-automaticswitching device to be used in the device of the present invention;

FIG. 9 is a perspective, exploded view illustrating the device of thepresent invention;

FIGS. 10 and 11 are graphical line diagrams showing the motions of thespeed-changing mechanism of the device of the present invention.

Referring to the drawings, wherein the same or equivalent parts aredesignated respectively by the same reference numeral 1 designates thesewing machine arm 1 in which a main driving shaft 2 is supportedrotatably on horizontal bearings. Rotation of said main shaft 2 issupported rotatably on horizontal bearings. Rotation of said main shaft2 is transmitted though a balance weight 3, a crank pin 4 a crank rod 5,and a needle bar pin 6 to actuate a needle bar 7 in an up-and-downmotion. At the same time, said rotation of the main shaft 2 istransmitted through a spiral gear 8 fixed 0n the main shaft 2 3,654,603Patented Nov. 20, 1962 and another spiral gear 9, which is enmeshedperpendicularly with the gear 8, to rotate a triangular cam 10 which inturn causes a forked rod 11, engaged as a follower with said cam 10, tooscillate. This oscillation is transmitted through a pin 12 at the lowerend of said forked arm 11 to oscillate a needle bar swinging frame 14,which under-goes a pendulum motion with a pin 13, fixed to the arm 1, asits fulcrum point. The resultant motion imparted to the needle bar 7 isa zigzag sewing motion.

The zigzag amplitude is controlled by manipulation of the zigzag controlknob 15 on the front surface of the arm 1, the motions thereof beingtransmitted through a shaft 16, and arm 17, a roller 18, and a fork 19to adjust the angle of the guide slot of a zigzag guide bracket 22,which guides the slide block 21 supported pivotally on a pin 21} on theforked rod 11.

On one hand, an automatic operation arm 26 is connected to an arm 23 ofthe zigzag guide bracket 22 through a pin 24 and a link 25, andautomatic control of the zigzag amplitude is effected by an automaticoperation cam 29 acting through a switching pawl 27 and a follower arm28.

A boss 36) of the automatic operation arm 26 is fitted to rotate freelyon a shaft 34, which is fixed by a nut 33 to a boss 32 of an automaticoperation base plate 31. In addition, the follower arm 28 is pivoted ona shaft 34, and a roller 36 mounted on said follower arm 28 is forced bya spring 35 to press in close contact against the peripheral contour ofthe automatic operation cam 29. The switching pawl 27 is supportedpivotally by a pin 37 to the arm 28. The free tip of the switching pawl27 is forced by a spring 38 to press in close contact against the boss30, and manual-automaticswitching is effected by the engagement anddisengagement of the said pawl tip with and from a slot 39 in boss 30.

Referring to FIGS. 6, 7, and 8, When the automatic operation cam 29 isnot inserted as shown in FIG. 6, the tip of the follower arm 28 passesthe bottom diameter of the automatic operation cam 29 and is shifted tothe left; an adjustable stop 49 of the switching pawl 27 strikes an edge41 of the automatic operation base plate 31; the switching pawl 27 isdisengaged from the slot 39; the automatic operation arm 26 becomes freeto rotate; and the mechanism is then in the manual operation condition.

Then, if a cam cover 42 is opened, an arm 46 supported pivotally on pin45 of the automatic operation base plate 31 is pushed in the directionof the arrow in FIG. 7 by a protruding arm 44 provided on a hinge 43,and a roller 36 is shifted to the outer side of the outer periphery ofthe automatic operation cam 29. The insertion of the automatic operationcam 29 is thereby facilitated. At the same time, the switching pawl 27engages with the the slot 39; the follower arm 28 and automaticoperation arm 26 are locked integrally with each other; and theoperation becomes automatic. Stop 40 is so adjusted that the saidengagement is maintained constantly while the automatic operation cam 29is being used, as shown in FIG. 8.

The details of the speed-changing mechanism of the automatic operationcam device will be more apparent by reference to the following detaileddescription. A cam shaft 48 is inserted rotatably in a vertical positionin the center of the automatic operation base plate 31, which is fixed,by means of screws 47 to the machine arm 1. A lock pin 49 and a snapring 50 of the automatic operation cam 29 are provided on the upperprotruding end, onto which the automatic operation cam 29 is fitted, ofsaid cam shaft 48. A small spiral gear 53 with an inclined angle isfixed by a pin 51 and nut 52 to the lower part of the said cam shaft 48.In an extended boss 54 on the lower face of the base plate 31, a

free-wheel shaft 55 is" supported rotatably'on a hori zontal axis, andat one end thereof, opposite gear 53, a large spiral gear 56 with aninclined angle is enmeshed at right angles with said gear 53, said gear56 being fixed by a pin 57 and a nut 58 and transmitting the rotationalmotion of the free-wheel shaft 55 to the cam shaft 48. At the same time,the inclined angle of said gear 56 being approximately 70 degrees ormore, said gear 56 cuts off any transmission of rotational motion fromthe cam shaft 48 to free-wheel shaft 55.

The other end of the free-wheel shaft 55 is provided with free-wheelplates 61 and 62, both of the same operational direction, with a spacer63 disposed therebetween, each of said plates having two rollers 59 andtwo springs 60. Said plate 61 is fixed to the boss 54 by a knock pin 64and screws 65. One end 68 of a forked rod. 67 is supported pivotally bya pin 69 and a nut 70 to the lower protruding end 66 of the plate 62.The end face of the assembly is closed by a washer 71 and a screw 72.The fork prongs 73 of the forked rod 67 are engaged with a triangularcam 74, which is constructed integrally as a single piece with gear 9and triangular cam 10. The rotation of the triangular cam 74 causes theforked rod 67 to oscillatev and, simultaneously, causes the lower endboss 75 to be guided, through a slide block 77 supported pivotally on apin 76 screwed in and fixed to said boss 75, by a groove 79 in a patternguide bracket 78 and to slide along the direction of said groove 79.

The guide bracket 78 has a hollow shaft 80, which is supported by arm 1on the same axis as the shaft 16 of the zigzag control knob, and isoperated by a pattern control lever 82, which is fixed by screws 81 tothe shaft 80 extending out to the front face of arm 1. Pin 83 is a stop,and poppet pin 84 and spring 85 are a click-stop or poppet lock forlever 82. A spring washer 86 placed at the interior surface of the arm 1for hollow shaft 80 and a spring washer 87 placed at the rear side ofarm 1 for the zigzag knob shaft 16 enable both said shafts to beoperated independently without mutual interference.

If the groove 79 of the pattern guide bracket 78 is adjusted by themanipulation of a pattern control lever 82, as shown in FIG. 10, forkedrod 67, through the action of the triangular cam 74 and guide groove 79,will undergo only an oscillatory motion with the pin 69 as the axis ofoscillation, and the cam shaft 48 Will notundergo' any rotational motionwhatsoever, the rotational ratio thereof with.respect to the main shaft2 being zero. However, when adjustment is made 'as shown in FIG. 11,forked rod 67, at the same time that it is oscillated by the triangularcam 74, is made by the guide groove 79 to undergo a reciprocating motionas shown by the arrow. The resulting'oscillation ofthe plate 62 causesthe shaft 55, through the free-wheel 62 and re verse-rotation-preventingfree-wheel 61, to rotate intermittently in one direction and to transmita rotation to the cam shaft 48 through the gears 56 and 53. Thisrotation can be varied freely as necessary by-the manipulation of thelever 82, which motion is converted into adjustment of the directionalangle of the guide groove 79 of the guide bracket 78, from zero toanyyalue within the predesigned range limited by the stop 83.Accordingly, the rotational ratio between the cam shaft 48 and mainshaft 2 can be varied steplessly from zero, within the above-mentionedrange. Moreover, through the use of the mechanism described above ofthis invention, speed. variation can be attained simply and freely. Atthe same time, rotation is effected quietly and reliably by thefree-wheeling mechanism, and any brakeless motion of the cam shaft 48 inthe rotational direction is prevented by the gears 53 and 56.Furthermore, through the use of the triangular cam 74 of coaxially,symmetrically opposite profile with respect to the triangular cam 10 foroscillating the needle bar, the possibility of rotation ofautomaticoperation cam 29 during the cloth-piercing motion of the needleis eliminated, yet the balance of the forked rods 11 and 67 with respectto vibration is excellent. Accordingly, the device of this invention isan ideal speed-varying, automatic cam device for usewithin an automaticzigzag sewing machine.

While only one particular embodiment of the present invention has beendescribed herein, it will, of course, be understood that the inventionis not to be limited to the details described herein, since manymodifications may be made in the said details without departing from thenature and spirit of the invention, and it is intended that all suchmodifications shall be covered by the ap pended claim.

What we claim is:

In a zigzag sewing machine having a maindrive shaft operativelyconnected to a needle bar controlled by a pattern cam for automaticallyguiding the needle bar through a zigzag movement, and an. arrangementfor controlling the speed of said cam, comprising in combination; firstand second mutually parallel shafts respectively disposed above'andbelow and normal to said drive shaft, first and second control camssecured in substantially balanced and spaced relation on said firstshaft, a first intermediately pivoted, bifurcated lever having abifurcated portion engaged on one of said cams and operatively connectedto said needle bar for affording a lateral oscillatory movement to saidneedle bar, a second bifurcated lever having a bifurcated portionengaged on said other control cam, a one-way drive mechanism operativelyconnected to said second bifurcated lever for operative connection tosaid pattern cam and for providing unidirectional and intermittentspeeds of movement to the pattern cam, and a control mechanism on saidsecond bifurcated lever for controlling the angular throw of said secondlever for obtaining variations of the speed ratio between the main driveshaft and the pattern cam, said control mechanism including a slideblock pivotally mounted on said second lever with an axis of rotationparallel to said first and second shafts, a bracket on said second shaftand rotatable therewith and. reciprocably receiving said slide block,means connected to saidsecond shaft for rotating said shaft and bracketabout the longitudinal axis of said second shaft to change the angularposition of said bracket and thereby change the motion of said slideblock to permit varying degrees of oscillation of said second bifurcatedlever from zero to a predetermined value and thereby varying the speedof rotation of the pattern cam.

References Cited in the file of this patent UNITED STATES PATENTS-2,757,626 Fujita Aug. 7, 1956 2,832,302 Gegauf Apr. 29, 1958 2,854,935Benink et al. Oct. 7, 1958 2,900,937 Gegauf Aug. 25, 1959 2,905,119 HomeSept. 22, 1959 2,929,344 Theenhausen et a1. Mar. 22, 1960 2,966,868Theenhausen et al Jan. 3, 1961

